#define _CRT_SECURE_NO_WARNINGS 1

#include<stdio.h>

int way_number(int x)
{
	int arr[100] = { 0 };
	arr[0] = 1;
	arr[1] = 1;
	int i = 0;
	for (i = 2; i <= x; i++)
	{
		arr[i] = arr[i - 1] + arr[i - 2];
	}
	return arr[x];
}

int main()
{
	int step = 0;
	int a = 0;
	scanf("%d", &step);
	a = way_number(step);
	printf("%d", a);
	return 0;
}